Redrawing district lines is driven by a constitutional requirement that each district have about the same population. In April, the Census Bureau reported that the state’s population grew 15 percent to more than 3.1 million. “If you're a Democrat, I think the reasonable goal is how do you keep the delegation three-to-one Democratic for the rest of the decade,” said Kyle Kondik, managing editor of Larry Sabato's Crystal Ball at the University of Virginia Center for Politics.